December 20, 2017
Summary: A fast moving cold front is currently moving down the valley. As of the time of this writing, the frontal band was almost to Monterey and Merced Counties and it will reach Fresno County about 8:00am or so and Kern County by midday. Doppler Radar is indicating light showers have spread as far south as northern Kern County but radar is also indicating the precipitation, as expected, is very light. The parent low is currently in northwest California and will dive into the Great Basin this afternoon, carving out a new low over Utah and northern Arizona. Upper level high pressure will begin to build northward along the Pacific coast, generating a north/northwest push of cold air down the valley.
Tonight’s forecast will be difficult for me, mainly due to mixing and wind conditions which certainly could help keep temperatures at acceptable levels. We could see upslope clouds in Kern County and portions of southeastern Tulare County, but as the dry air moves inland, these clouds will eventually evaporate.
Models show very cold mornings coming up Friday and Saturday as upper level high pressure once again puts a lid on the situation with little to no wind and a cold air mass. Low to mid 20s will be possible. It appears this will be the beginning of a series of very cold nights which will last until after Christmas, and even then it will require an exchange of air masses to really break the back of the cold nights.
Daytime highs, though, will begin to moderate over the weekend and will actually move above average, even though overnight lows will continue cold.
So far models for the period between Christmas and New Year’s favor a dry, blocking pattern which will not allow Pacific storms to affect California.
Forecast: Mostly cloudy with scattered light showers possible, mainly this morning. Clearing this afternoon. Becoming mostly clear tonight and Thursday except possibly remaining cloudy over portions of Kern County and southeastern Tulare County. Mostly clear Thursday afternoon through Wednesday.
Short Term:
| Madera 54/26/53/22/56 | Reedley 55/25/52/23/57 | Dinuba 53/24/53/21/56 | |
| Porterville 56/26/53/23/57 | Lindsay 55/25/53/22/57 | Delano 56/27/53/24/57 | |
| Bakersfield 56/34/53/27/58 | Arvin 54/28/54/23/58 | Taft 56/34/53/27/59 | |
| Lamont 55/28/54/23/59 | Pixley 55/26/53/22/57 | Tulare 54/25/53/22/56 | |
| Woodlake 55/26/53/22/57 | Hanford 55/26/53/22/56 | Orosi 55/25/53/22/57 | |
Seven Day Forecast:
| Saturday
Mostly clear 25/58 |
Sunday
Mostly clear 27/64 |
Christmas Day
Mostly clear 27/67 |
Tuesday
Mostly clear 28/68 |
Wednesday
Partly cloudy 29/59 |
Two Week Outlook: December 26 through January 1: Models for this time frame are somewhat inconclusive. They do call for below average precipitation with temperatures close to seasonal values, this would be highs in the mid 50s and lows in the upper 20s to the mid 30s. The chance of precipitation remains low.
December: This model is indicating a better than even chance of above average temperatures for central and southern California all the way to the southeast with near to below average temperatures in the Pacific Northwest. As far as precipitation is concerned, this model does show better than average precip over Washington and Oregon and near average rainfall over central and northern California.
December, January, February: If this model is to be believed, winter this year will experience somewhat above average temperatures from California, stretching eastward and southward. Below average temperatures would prevail from the northern Rockies through the Plains states. As far as California is concerned, precipitation would be near to marginally below average with temperatures marginally above average, but take all this with a grain of salt.
Winds: Winds later today will be out of the northwest at 10 to 15 MPH with the exception of the west side, mainly north of Kern County, where winds will increase to 15 to 15 MPH with stronger gusts. Winds tonight will be light after midnight with the exception of the west side where winds will be out of the northwest at 10 to 15 MPH with stronger gusts, diminishing before sunrise. Winds Thursday through Saturday will be generally less than 10 MPH with periods of near calm conditions.
Rain: Doppler radar is indicating light showers have quickly progressed as far south as Kern County. The chance of light showers will continue this morning, but will be over by midday at most locations. Lift will ensure a bit heavier amounts will fall in the Sierra Nevada, but even there no more than a quarter of an inch is expected at most locations with rain totals of no more than a few hundredths of an inch on the valley floor. Many locations will remain dry.
This afternoon through what may be New Year’s Day may be dry, barring any surprises.
Frost: A moisture starved but rather dynamic cold front is currently moving rapidly down the valley with a few very light showers. The current position of the cold front is moving through Merced County. It will reach Kern County by midday.
The cold parent low is in northwest California and will take a dive into the Great Basin this afternoon. Cold air will swoop in southward on the back side of the low, setting the stage for what could be very cold weather beginning tonight, but more so Friday morning and on through Christmas morning.
Tonight’s forecast will be difficult to nail down as wind conditions and mixing behind the low will be evident. Winds along the west side may keep temperatures in the upper 20s to even above freezing, tnough if the winds die off, temperatures will plummet. There’s a better chance, at least in some areas, of mid 20s along the east side, particularly the closer one gets to the Sierra Nevada, but even there mixing and wind conditions may play a role.
Durations for tonight will be variable. The inversion will be weak with temperatures at 34 feet ranging from 2 to 5 degrees warmer at most locations. That should firm up a bit Friday morning.
The wild card in Kern County and possibly southeastern Tulare County could be upslope clouds. Models show these clouds mixing out tonight, but experience tells me this won’t necessarily be the case. Still, if these clouds do disperse, mid 20s will be possible in the coldest locations in Kern County, as well.
Friday morning and Saturday have the potential to be very cold as generally clear skies will prevail with little to no wind, a combo that will set the stage for strong radiational cooling in what will become a cold, dry air mass. It’s always possible models could be overzealous as one model places Porterville at 28 Thursday morning while others show as low as 23, putting frost pockets in a dangerous situation, if unprotected.
Durations could potentially be quite long with below freezing conditions lasting through to about 9:00 Friday morning.
Saturday morning appears no better with only marginal modification of daytime highs. Mid to upper 20s appear to be a good bet for Christmas Eve and Christmas Day with the possibility of riverbottom and similar low spots in the low 20s.
After Christmas, daytime highs will move possibly into the mid to upper 60s which should begin to drag up overnight lows a bit. But as we have learned this month, that is a painfully slow process.
Lows Tonight:
| Terra Bella
25 |
Porterville
27 |
Ivanhoe
26 |
Woodlake
26 |
| Strathmore
26 |
McFarland
25 |
Ducor
26 |
Tea Pot Dome
26 |
| Lindsay
25 |
Exeter
24 |
Famoso
28 |
Madera
26 |
| Belridge
28 |
Delano
28 |
North Bakersfield
27 |
Orosi
25 |
| Orange Cove
26 |
Lindcove
25 |
Lindcove Hillside
30 |
Sanger River Bottom
23 |
| Root Creek
24 |
Venice Hill
27 |
Rosedale
28 |
Jasmine
27 |
| Arvin
26 |
Lamont
26 |
Plainview
26 |
Mettler
29 |
| Edison
27 |
Maricopa
26 |
Holland Creek
29 |
Tivy Valley
26 |
| Kite Road South
28 |
Kite Road North
26 |
AF=Above Freezing
Afternoon Dew Points Today: Upper 20s to the lower 30s. Kern, low to mid 30s.
Humidity: 45%/95% Bakersfield, 50%/75%
Actual Humidity December 18, 2017: Delano, NA, Porterville, 90%/24%
Percentage of Sunshine Today/Tomorrow: Visalia: Today 30% tomorrow 80%, Bakersfield: Today 10% tomorrow 70%.
ET Rates Over the Past Seven Days December 18, 2017: Stratford .45, Parlier .36, Blackwell, .53 Lindcove .38, Arvin .49, Orange Cove .43, Porterville .36, Delano .NA., Madera Two .36. Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 49, Parlier 49, Blackwell 53, Lindcove, 54, Arvin, 52, Orange Cove 49, Porterville 49, Delano NA, Madera Two 51
Mean Temperatures for December. Month So Far: 47.0 +2.0
Record Temperatures: 74/25. Average Temperatures: 54/35
Heating Degree Days this Season: 624, -232 Courtesy of the NWS
Precipitation: Seasonal total/average/above or below average:
Since December 18, 2017 Fresno: .37 season. or -2.22. Month to Date: T
Since December 18, 2017, Bakersfield: .03, or -1.44, Month to Date: ..00
Water year season is from October 1st through September.
Chilling ours November 1st through February 28: Orange Cove, 331, Parlier, 350, Arvin, 285, Shafter, 397, Stratford, 351, Madera two, 501, Alpaugh, NA, Delano, NA, Lindcove, 328, Porterville, 481. Hours at 45 or below 45.
Sunrise: 7:07 am Sunset: 4:46 pm. Hours of Daylight: 9:38
Yesterday’s Weather:
MAE : Madera 253 : DH1600 / 64 / 30 / 0.00 /
FAT : Fresno Airport 333 : DH1600 / 64 / 35 / 0.00 /
HJO : Hanford Airport 242 : DH1600 / 65 / 47 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1600 / 64 / 27 / 0.00 /
BFL : Bakersfield Airport 496 : DH1600 / 68 / 36 / 0.00 /
VIS : Visalia Airport 292 : DH1600 / 64 / 32 / 0.00 /
ATEC1 : Avenal 787 : DH1557 / 66 / 33 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 68 / 31 / 0.00 /
TFTC1 : Taft 759 : DH1557 / 64 / 33 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 62 / 35 / 0.00 /
Rainfall: Season % Last y. % Ave. Annual Ave.
STOCKTON 0.00 0.91 24 5.46 144 3.78 14.06
MODESTO 0.00 0.98 31 4.30 135 3.18 13.11
MERCED 0.00 1.03 38 3.72 136 2.74 12.50
MADERA 0.00 0.32 11 3.62 124 2.91 12.02
FRESNO 0.00 0.37 14 4.08 154 2.65 11.50
HANFORD 0.00 0.37 17 2.00 92 2.18 10.10
BAKERSFIELD 0.00 0.03 2 1.02 68 1.51 6.47
BISHOP 0.00 0.16 13 0.15 12 1.22 5.18
SALINAS 0.00 0.75 24 3.82 124 3.08 12.83
PASO ROBLES 0.00 0.25 9 3.40 125 2.73 12.78
SANTA MARIA 0.00 0.09 3 4.02 130 3.09 13.95
Next Report: Wednesday, December 20/pm